SanDisk 4 GB Extreme III Compact Flash - 1 $24.95 (after rebate)
SanDisk 4 GB Extreme III Compact Flash - 3 pk $33 (after rebate)
SanDisk 8 GB Extreme III Compact Flash - 1 $39.95 (after rebate)
SanDisk 8 GB Extreme III Compact Flash - 3 pk $66 (after rebate)
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SanDisk 4 GB Extreme III Secure Digital (SDHC) - 3 pk $24 (after rebate)
SanDisk 8 GB Extreme III Secure Digital (SDHC) - 1 $34.95 (after rebate)
SanDisk 8 GB Extreme III Secure Digital (SDHC) - 3 pk $57 (after rebate)
Yes, you read that correctly, it's actually less expensive (final cost) to buy three 4 GB SDHC cards than it is to buy one, go figure.
The rebate form is available for download here.